Chair adjusting device

ABSTRACT

A chair adjusting device includes a seat support board, a base, a backrest linking base, two elastic sets, and a backrest. The two elastic sets may provide an auxiliary elastic force to the backrest linking base. The seat support board has a rear side slidably mounted on the two side plates of the backrest linking base by two pivot knobs, so that the seat support board may be moved in concert with the backrest linking base. A primary urging spring is mounted on the support rod, and has a top edge urged on a bottom face of the seat support board.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a chair adjusting device, andmore particularly to a chair adjusting device that may entirely satisfythe ergonomic requirements and may adjust the inclined angle between theseat and the backrest automatically and synchronously, such that theuser may obtain comfortable sensation.

[0003] 2. Description of the Related Art

[0004] A conventional chair comprises a seat and a backrest. When thebackrest is adjusted to have an inclined angle so as to fit the user'srequirement, the seat is also moved with the backrest to have aninclined angle, so that the front side of the seat is liftedsynchronously. However, the inner side of the user's leg is compressedby the inclined front side of the seat, thereby easily causinguncomfortable sensation to the user during long-term utilization, andthereby easily poorly affecting the blood circulation of the user.

[0005] The closest prior art of which the applicant is aware isdisclosed in the Taiwanese Patent Publication No. 239946, entitled by“Base Structure of Chair”.

[0006] In the Taiwanese Patent Publication No. 239946, the two springsfunction as the primary springs, and are the only source of the elasticforce. In addition, when the backrest is inclined backward, the seat isnot inclined backward with the backrest. Further, the elastic force ofthe two primary springs cannot be adjusted. Further, all of the elasticforce of the two primary springs is concentrated on the backrest linkingbase, thereby easily producing a stress concentration point.

SUMMARY OF THE INVENTION

[0007] The primary objective of the present invention is to provide achair adjusting device that may entirely satisfy the ergonomicrequirements, and may adjust the inclined angle between the seat and thebackrest automatically and synchronously, so that the user may have acomfortable sensation.

[0008] Another objective of the present invention is to provide a chairadjusting device, wherein the elastic force of the primary urging springand the two auxiliary springs of the two elastic sets may be evenlydistributed on the seat support board, the backrest linking base, andthe L-shaped backrest, thereby preventing from producing a stressconcentration point.

[0009] In accordance with the present invention, there is provided achair adjusting device, comprising: a seat support board, a base, abackrest linking base, two elastic sets, and a backrest, wherein:

[0010] the seat support board has a front side provided with two obliquesupport racks, the front side of the seat support board is formed with ashaft hole, and a first shaft is extended through the shaft hole, sothat the front side of the seat support board is pivotally mounted onthe base, the seat support board has a rear side slidably mounted on twoside plates of the backrest linking base by two pivot knobs, so that theseat support board may be moved in concert with the backrest linkingbase;

[0011] the base has two side plates for passage of a second shaft, sothat the backrest linking base may be pivotally mounted on the two sideplates of the base by the second shaft, a support rod is screwed andpositioned between the two side plates of the base, a primary urgingspring is mounted on the support rod, and has a top edge urged on abottom face of the seat support board;

[0012] the backrest linking base is pivotally mounted on the base by thesecond shaft, and front ends of the two side plates of the backrestlinking base are symmetrically pivoted with two elastic setsrespectively; and

[0013] each of the two elastic sets includes two pivot bases, a sliderod, and an auxiliary spring, a first one of the two pivot bases of eachof the two elastic sets is positioned between the two side plates of thebase by a third shaft, and a second one of the two pivot bases of eachof the two elastic sets is pivoted and positioned on the front end ofeach of the two side plates of the backrest linking base, so that thebackrest linking base is constantly subjected to an auxiliary elasticforce by the two elastic sets.

[0014] Further benefits and advantages of the present invention willbecome apparent after a careful reading of the detailed description withappropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a perspective assembly view of a chair adjusting devicein accordance with a preferred embodiment of the present invention;

[0016]FIG. 2 is an exploded perspective view of the chair adjustingdevice as shown in FIG. 1;

[0017]FIG. 3 is a partially exploded perspective view of the chairadjusting device as shown in FIG. 1;

[0018]FIG. 4 is a side plan cross-sectional view of the chair adjustingdevice as shown in FIG. 1; and

[0019]FIG. 5 is a schematic operational view of the chair adjustingdevice as shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Referring to the drawings and initially to FIGS. 1-3, a chairadjusting device in accordance with a preferred embodiment of thepresent invention comprises a seat support board 10, a base 20, abackrest linking base 30, two elastic sets 40, and a backrest 50.

[0021] The seat support board 10 has a front side provided with twooblique support racks 11, so that a seat (not shown) may be threadedlysecured on the two support racks 11. The front side of the seat supportboard 10 is formed with a shaft hole 15, and a shaft 25 is extendedthrough the shaft hole 15, whereby the front side of the seat supportboard 10 is pivotally mounted on the base 20, so that the shaft 25 mayfunction as the rotation shaft of the seat support board 10.

[0022] The seat support board 10 has a rear side formed with twoopposite slide slots 16 for passage of two pivot knobs 36, whereby therear side of the seat support board 10 may be slidably mounted on thetwo side plates of the backrest linking base 30 by the two pivot knobs36, so that the seat support board 10 may be moved in concert with thebackrest linking base 30.

[0023] The base 20 is secured on a foot post 28, and has two side platesfor passage of a shaft 26, so that the backrest linking base 30 may bepivotally mounted on the two side plates of the base 20.

[0024] A support rod 21 is screwed and positioned on the two side platesof the base 20. A primary urging spring 22 is mounted on the support rod21, and has a top edge urged on a bottom face of the seat support board10.

[0025] A hook rod 23 is extended through a bottom face of the base 20,and has a top end hooked on a side edge of the primary urging spring 22,and a bottom end screwed into a locking sleeve 29. The locking sleeve 29may be rotated to move the hook rod 23, thereby adjusting the upwardurging force of the primary urging spring 22, so as to fit therequirements of different users.

[0026] The backrest linking base 30 is pivotally mounted on the two sideplates of the base 20 by the shaft 26, so that the shaft 26 may functionas a rotation shaft of the backrest linking base 30.

[0027] An L-shaped backrest 50 is threadedly secured on a rear side ofthe backrest linking base 30, and a backrest cushion (not shown) may bemounted on the backrest 50.

[0028] The rear side of the seat support board 10 is slidably mounted onthe two side plates of the backrest linking base 30 by the two pivotknobs 36, so that the seat support board 10 may be moved in concert withthe backrest linking base 30. The front ends of the two side plates ofthe backrest linking base 30 are symmetrically pivoted with two elasticsets 40 respectively.

[0029] Each of the two elastic sets 40 includes two pivot bases 41, aslide rod 42, and an auxiliary spring 43. A first one of the two pivotbases 41 of each of the two elastic sets 40 is positioned between thetwo side plates of the base 20 by a shaft 24. The auxiliary spring 43 ismounted on the slide rod 42 which is slidably pivoted between the twopivot bases 41. A second one of the two pivot bases 41 of each of thetwo elastic sets 40 is pivoted and positioned on the front end of eachof the two side plates of the backrest linking base 30 by two shaft pins39, so that the backrest linking base 30 and the L-shaped backrest 50are constantly subjected to a clockwise auxiliary elastic force by thetwo elastic sets 40 as shown in FIG. 4.

[0030] Referring to FIGS. 1-5, in the chair adjusting device inaccordance with a preferred embodiment of the present invention, the twoslightly inclined elastic sets 40 may provide an auxiliary elastic forceto the backrest linking base 30 and the L-shaped backrest 50, and therear side of the seat support board 10 is slidably mounted on the twoside plates of the backrest linking base 30 by the two pivot knobs 36,so that the seat support board 10 may be moved in concert with thebackrest linking base 30. The primary urging spring 22 is urged on thebottom face of the seat support board 10.

[0031] Thus, the elastic force of the primary urging spring 22 and thetwo auxiliary springs 43 of the two elastic sets 40 may be evenlydistributed on the seat support board 10, the backrest linking base 30,and the L-shaped backrest 50, thereby preventing from producing a stressconcentration point.

[0032] In addition, the elastic force of the primary urging spring 22and the two auxiliary springs 43 may be applied on the seat supportboard 10, the backrest linking base 30, and the L-shaped backrest 50synchronously.

[0033] Further, the locking sleeve 29 may be rotated to move the hookrod 23, thereby adjusting the upward urging force of the primary urgingspring 22 on the seat support board 10.

[0034] Accordingly, the primary urging spring 22 and the two auxiliarysprings 43 of the two elastic sets 40 may apply an auxiliary elasticforce to the seat support board 10 and the backrest linking base 30, sothat the seat support board 10 and the backrest linking base 30 may berotated relative to the base 20 synchronously. Thus, the chair adjustingdevice of the present invention may entirely satisfy the ergonomicrequirements, and may adjust the inclined angle between the seat and thebackrest automatically and synchronously, so that the user may have acomfortable sensation.

[0035] In comparison, in the Taiwanese Patent Publication No. 239946,the two springs function as the primary springs, and are the only sourceof the elastic force. In addition, when the backrest is inclinedbackward, the seat is not inclined backward with the backrest. Further,the elastic force of the two primary springs cannot be adjusted.Further, all of the elastic force of the two primary springs isconcentrated on the backrest linking base, thereby easily producing astress concentration point.

[0036] In the present invention, the primary urging spring 22 functionsas the primary spring, and the two auxiliary springs 43 of the twoelastic sets 40 only provide an auxiliary elastic force. In addition,when the backrest 50 is inclined backward, the seat support board 10 andthe backrest linking base 30 are also inclined backward with thebackrest 50. Further, the locking sleeve 29 may be rotated to move thehook rod 23, thereby adjusting the upward urging force of the primaryurging spring 22, so as to fit the requirements of different users.Further, the elastic force of the primary urging spring 22 and the twoauxiliary springs 43 of the two elastic sets 40 may be evenlydistributed on the seat support board 10, the backrest linking base 30,and the L-shaped backrest 50, thereby preventing from producing a stressconcentration point.

[0037] Although the invention has been explained in relation to itspreferred embodiment as mentioned above, it is to be understood thatmany other possible modifications and variations can be made withoutdeparting from the scope of the present invention. It is, therefore,contemplated that the appended claim or claims will cover suchmodifications and variations that fall within the true scope of theinvention.

What is claimed is:
 1. A chair adjusting device, comprising: a seatsupport board, a base, a backrest linking base, two elastic sets, and abackrest, wherein: the seat support board has a front side provided withtwo oblique support racks, the front side of the seat support board isformed with a shaft hole, and a first shaft is extended through theshaft hole, so that the front side of the seat support board ispivotally mounted on the base, the seat support board has a rear sideslidably mounted on two side plates of the backrest linking base by twopivot knobs, so that the seat support board may be moved in concert withthe backrest linking base; the base has two side plates for passage of asecond shaft, so that the backrest linking base may be pivotally mountedon the two side plates of the base by the second shaft, a support rod isscrewed and positioned between the two side plates of the base, aprimary urging spring is mounted on the support rod, and has a top edgeurged on a bottom face of the seat support board; the backrest linkingbase is pivotally mounted on the base by the second shaft, and frontends of the two side plates of the backrest linking base aresymmetrically pivoted with two elastic sets respectively; and each ofthe two elastic sets includes two pivot bases, a slide rod, and anauxiliary spring, a first one of the two pivot bases of each of the twoelastic sets is positioned between the two side plates of the base by athird shaft, and a second one of the two pivot bases of each of the twoelastic sets is pivoted and positioned on the front end of each of thetwo side plates of the backrest linking base, so that the backrestlinking base is constantly subjected to an auxiliary elastic force bythe two elastic sets.
 2. The chair adjusting device in accordance withclaim 1, wherein the base is secured on a foot post.
 3. The chairadjusting device in accordance with claim 1, further comprising a hookrod extended through a bottom face of the base, wherein the hook rod hasa top end hooked on a side edge of the primary urging spring, and abottom end screwed into a locking sleeve.
 4. The chair adjusting devicein accordance with claim 1, wherein the backrest is L-shaped, and isthreadedly secured on a rear side of the backrest linking base.
 5. Thechair adjusting device in accordance with claim 1, wherein the auxiliaryspring is mounted on the slide rod which is slidably pivoted between thetwo pivot bases.